Plasma secretin concentrations during normal human pregnancy, delivery, and postpartum.

Plasma concentrations of secretin were measured at 4-week intervals throughout eight normal pregnancies and again twice postpartum, and in another six women during parturition and the early postpartum period. Comparisons were made with levels in 16 normal non-pregnant women. Plasma secretin concentrations increased during pregnancy with maximum levels at 36 weeks. The increase was statistically significant from week 28 to 36, compared with non-pregnant levels. By 5 days after delivery plasma secretin levels were similar to the non-pregnant levels. No significant changes in plasma secretin were observed during delivery and early postpartum. The altered secretin levels may be of importance for heartburn in pregnancy, calcium metabolism, and the changes in renal haemodynamics.